Human fetal whole body post-mortem microfocus computed tomographic imaging

Pregnancy loss is a devastating event and whilst conventional autopsy techniques can provide parents with answers as to the cause of their loss, many decline due to its invasive nature. We describe micro-CT as an alternative to conventional autopsy and why this is more acceptable to parents.

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The loss of a child is a traumatic event and more common than many people would expect.  It is estimated that 1 in 4 pregnancies end in a miscarriage, and over 2500 stillbirths occur each year in the UK (1, 2).  Many parents want to find out why their baby has died, but equally still feel a sense of protection over their baby; wishing that no further harm is inflicted to the body, and sometimes religious beliefs play a role in guiding their choices.  Although an autopsy is the most comprehensive medical investigation, this has traditionally involved making large incisions to the body and is now considered unacceptable to most parents (approximately 60% of parents decline this investigation (3, 4).  This means that parents and clinicians may miss out on valuable information about why the baby died, which could be important for managing future pregnancies.

Although many clinical imaging tests (such as x-rays, ultrasound, computed tomography (CT) and magnetic resonance imaging(MRI)) offer alternative non-invasive methods for imaging the deceased, these do not provide the required detail required to evaluate early miscarriages (below 20 weeks gestational age), when the majority of miscarriages occur and the fetus can be very small.

Micro-computed tomography (micro-CT) is an imaging technique that has been mostly used in laboratories and in industry to image extremely small structures down to 10 microns – or 0.01 millimetres!  It uses x-rays in a set-up very similar to how medical CT scanners work and allows highly detailed 3-dimensional images to be created.  Until now, it has not been routinely used in a hospital clinical setting on humans.

 Our pioneering work since 2016 has demonstrated that using this micro-CT technology we can identify abnormalities in fetuses from early pregnancy loss which may have been responsible for the pregnancy loss.  Through our extensive experience in scanning over 500 fetuses and the abnormalities we have detected, we have demonstrated how useful this technique can be in this patient setting.  We have overcome many obstacles to develop a suitable protocol for this new imaging method, requiring a multi-disciplinary collaborative approach from several members of our radiology, pathology and mortuary staff at Great Ormond Street Hospital for Sick Children, London, UK.

 The first steps in the process are critical to get right.  Firstly, our pathologists review the clinical history and perform an external inspection of the fetus.  If small enough to benefit from micro-CT, the fetus then needs to be ‘prepared’ with a special stain (the so-called ‘iodination process’).  Standardisation and optimisation of the iodination process, fetus immobilisation methods during scanning, and imaging parameters of the micro-CT scanner to ensure a diagnostic quality and suitably magnified image have been developed from our local experience.  

Staff and patient education has been imperative in the uptake and adoption of this technique.  Ensuring that midwifery teams from our referral units can explain, discuss, and gain consent from bereaved parents for the micro-CT imaging procedure, is critical.  Without the understanding of the parents in entrusting their child to our team, our research would not have been possible.  Throughout the process we have discussed our technique with recently bereaved parents, as well as our key stakeholders which include religious leaders, midwives, pathologists, mortuary staff and pregnancy loss charities (3, 5).  This patient engagement conversation is essential in ensuring that our clinical service is fit for purpose and acceptable to as many patients and parents as possible, and we have seen an increasing demand for our micro-CT imaging each year.

Our goal in writing this protocol was to demonstrate and provide other researchers and imagers with our method for a non-invasive, high resolution and magnification imaging technique that helps us identify underlying causes for pregnancy loss in early gestational aged fetuses, for which no other imaging tool is readily available.  This increases the choice of investigations available to bereaved parents at the most difficult time of losing a child.  We hope that by making this technique available, more parents can find comfort from the value of finding out why their baby died and aid in future pregnancy management.

We would like to thank all bereaved parents who have participated in our preliminary studies, in helping to develop our services and in providing feedback to allow for our micro-CT technique to continue to improve.  Without them and their children, this work would never have been possible.  We thank them for their trust and teamwork.

Please use the following SharedIt link to access our paper  https://rdcu.be/ciGWK

  1. Statistics OfN. Births in England and Wales 2019. 2019.
  2. Tommy's. Miscarriage statistics 2021 [Available from: https://www.tommys.org/baby-loss-support/miscarriage-information-and-support/miscarriage-statistics#general.
  3. Lewis C, Hill M, Arthurs OJ, Hutchinson C, Chitty LS, Sebire NJ. Factors affecting uptake of postmortem examination in the prenatal, perinatal and paediatric setting. BJOG. 2018;125(2):172-81.
  4. Sieswerda-Hoogendoorn T, van Rijn RR. Current techniques in postmortem imaging with specific attention to paediatric applications. Pediatr Radiol. 2010;40(2):141-52; quiz 259.
  5. Lewis C, Hutchinson JC, Riddington M, Hill M, Arthurs OJ, Fisher J, et al. Minimally invasive autopsy for fetuses and children based on a combination of post-mortem MRI and endoscopic examination: a feasibility study. Health Technology Assessment. 2019;23(46):1-104.

 

Ian Simcock

Radiographer, Great Ormond Street Hospital for Sick Children

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